There's a theory in personal development circles that putting most energy into developing your strengths into "super-strengths" is a more effective pathway than improving your weakness' - providing none of your weakness' are "mission critical"
Where a weakness could be deemed "mission critical" (in other words it will hold you back in a major way), then it could/should be a focus for improvement. Otherwise, focus on developing your strengths.
I've not experimented much with this is a sporting context, but it is a theory gaining much ground in the corporate world and something I am experimenting with with a couple of athletes at the moment.
I tweet - @ashtennis guru (no spaces)
I Shoot - www.flickr.com/photos/ashtennis guru/ (again no spaces! grrr)